The Principal Investigator plans to study the synthesis of new molecules in the brain which accompany and make possible the storage of memories. The regions of the brain that are of most interest are the hippocampus and diencephalic regions, previously shown to have the maximum response to a learning event by increasing RNA and polyribosome synthesis. The molecular species that will be studied in detail are those proteins which increase in synthesis due to training in a fifteen minute active avoidance paradigm. The first generation hybrid of two inbred mouse strains will be the subjects (C57BL/6 females by DBA/2 males), and the proteins will be studied by electrophoretic, chromatographic, and enzymatic assay procedures. The roles which heterogeneous populations of brain ribosomal subunits play in the memory process will also be studied.